Circuit breaker system



Sept. 6, 1949. E. KERN 2,481,428

CIRCUIT BREAKER SYSTEM Filed Nov. 15, 1946 Patented Sept. 6, 1949 CIRCUIT BREAKER SYSTEM Erwin Kjern, Ennetbaden, Switzerland, assigner to Aktiengesellschaft Brown, Bover t Cie, Baden, Switzerland, a joint-stock company Application November 13, 1.946 Serial No. 709,463 In Switzerland November 1,6, 1945 2 Claims.

l In power lines, especially those in which energy is transmitted by means of high voltage direct current and which serve to feed a number of consumer branches, it is desirable7 when short crcuits occur in one of the branches, to confme the disturbance as promptly and infas localized a manner as possible so as to separate only the faulty consumer circuit from the network while yet permitting the unaiected branches to con'- tinue in operation. For this purpose it is necessary to incorporate high voltage switches in the high voltage direct current lines leading to the various consumer circuits. Switches of this sort have proven to be relatively unsatisiactory and there is a desire in the art to eliminate their use.

The present invention relates to a circuitbreaking method intended for the selective protection of a plurality of current consuming branches, fed from one side of a producing system, againstl disturbances that may occur in one of said branches, and also includes arrangements for practising said method and which permit of simplifying the circuit-breaking means used, the simplication introduced by the invention involving the breaking of the power circuit by means of a rapidly resetting power circuit` breaking device common to all consumer branches and the breaking of the voltage circuit in each cone sumer circuit by means of a separatory switch provided therein.

The drawings diagrammatically illustrate the invention by Way of an embodiment showing an arrangement for practising the circuit breaking method as. applied to a direct current high voltage transmission line which is fed by grid-cone trolled rectiers and adapted to feed a plurality of consumer branches..v More; particularly: v

Fig. 1 is a circuit diagram illustrating the invention.

Figs. 2 and 3 show various embodiments of the separatory switches and the operation thereof in the consumer branches.

The high voltage direct current produced by the rectifier i is transmitted by the line 2 and supplied to the consumer branches 3, 44 5 to which direct current power consuming devices of any desired type may be connected. The rectifier is. of the grid controlled type, adapted, upon the occurrence of an overload, to interrupt the passage of current for a brief interval and again close the circuit immediately, that is, it functions as a power circuit breaker. In the consumer branches, and as near as possible to the junction points, are separatory switches 6a, 6b, 6c which are arranged for automatic operation in response 2 to the magnitude or variation of current in the consumer branches and in such fashion that' the opening of the separatory switches will take place only if the disturbance in the consumer branches is of prolonged duration.

The separatory switches 6a, El?, 60, are each provided with release coils lc (see Figs. l and 2') energized by current transformers 8a, 8b, 8c in the consumer branches through intermediary relays se and itc. The relay tlc, in addition to contacts corresponding to its position ci restv and its operating position, is also provided with supplementary holding-circuit contacts. Therelay itc is provided with av dashpot return movement retarder. During normal operation, the relays 9c and lilo assume the position shown in Figs., 2 and 3, the separatory switches being in operative position in the consumer branches. The operat-I ing current for the actuating coil of the relay 8cV passes across the contacts of the relay Mic that correspond toits position of rest, whereas the circuit of relay I0c is arranged to become closed by the operating contacts of relay 9c.

If a short circuit occurs, for example in the consumer circuit 5, the rectier l becomes. inoperative (bl0cked) for a short period due to action of the grid control la thereof which iS instantaneously responsive to prevailing overload current surges, and the transmission of power t0.- the consumer branches will be temporarily interrupted. At the same time the rapidly increasing overload current passing through the primary coil of the current transformer 8c will engender a current surge in the secondary winding thereof which will rst actuate the relay 9c, The relay 9c, when iny operating position, will close the actuating circuit of the second relay ISC, the latter beincr provided with a dashpot return movement retarder. The relay itc in turn, when in Operating position, conditions the open. circuit of the release coil lc for closure by the relay 9c as it returns to its position of rest. The relay @c when in operating position also closes a; holding current circuit leading to its actuating coil. During the continuance of the overload current surge in the secondary winding of the transformer 8c both relays te and ille therefore assume their operat-` ing positions. When the overload surge subsides, the relay 9c returns to its position of rest and thereby closes the circuit of the release coil 'lc' of the separatory switch 6c.

If the operation of the grid control arrangement la of the rectier l and the temporary power interruption initiated thereby has permitted the cause of the disturbance in the consumer branch 5 to be eliminated, then, as the voltage is again restored to its high value, the current in the transformer 8c will rise relatively slowly to its proper value. The release coil will therefore not be actuated. However, if the disturbance in the consumer branch 5 persists after the power circuit has once been interrupted with the aid of the rectier I, then, as the voltage is raised, a fresh short circuit will occur and hence also a second current surge in the transformer 8c so that current will be fed to the release coil 'Ic to effect release of the separatory switch. At the same time however the grid control arrangement of the rectifier I comes into action and effects a second temporary power interruption. The result is that, on the occurrence of a disturbance in a power distribution system containing a plurality of consumer branches, the branch in which the disturbance occurs will be per se cut out only if the disturbance persists, so that operation of the unaffected consumer branches can continue undisturbed after a twice repeated temporary power interruption.

In lieu of operating the separatory switches in the consumer branches in response to the magnitude of the power current, it is also possible for this purpose to make them responsive to variations of the load current.

In lieu of the simple knife switches illustrated in Fig. 2 as embodiments of separatory switches suitable for use in the consumer branches, it is also possible to employ gas discharge tubes of the arc type in which the actuating arc is operated independently of the load current and in which the actuating arc does not restrike, such arrangement making it possible to eliminate persisting short circuits, as shown in Fig. 3. Moreover, a number of such gas discharge tubes may be employed in series and inserted in the consumer circuits to serve in lieu of separatory switches. The gas discharge tube I6 which serves as a separatory switch in Fig. 3 is provided with an energizing (starter) anode in addition to the regular anode and cathode, said starter anode being fed by a current source I5 that is independent of the load current. In lieu of the release coil 'Ic shown in Fig. 2, a relay I I is used in this case which, like release coil 'Ic is energized with the aid of relays 9c and Ic from the secondary of transformer 8c in the event of a persisting disturbance in the branch consumer circuit 5 as the main line is reclosed. As relay I1 is energized, the circuit between the starter anode and the source I5 is interrupted at the relay contacts thus extinguishing the actuating arc in the gas discharge tube I6, so that, here again, after a twice repeated brief power interruption, the disturbed branch will be cut 01T from the net. Restriking of the arc in the gas discharge tube I6 may also be prevented by impressing a suitable charge on the control grid that cooperates with the principal anode.

The circuit-breaking method and the embodiments shown for practising the same may also be employed in radio broadcasting systems of the type wherein a number of transmitter tubes are fed by a single rectier.

In addition to being applicable to direct current systems, the invention can also be used in alternating current systems. In such case the .4 common power interrupting breaker may be constituted as a switch provided with self-closing contacts and which is operated by gas under pressure, said switch being here again actuated by current surges, the separatory switches in the consumer branches however being constituted either as simple knife switches or gas discharge tubes, as described in reference to Figs. 2 and 3. The operation is the same as that explained for direct current operation. The power breaker, operated by gas pressure, may either be located at the junction points of the consumer branches or at the beginning of the transmission line.

In the case of polyphase alternating current consumer systems or in the case of multipolar direct current systems it is preferable so to arrange the circuits that when disturbances occur in more than one phase or poles, a lesser number of phases or poles will be cut out by actuation of the proper separatory switches than are affected by the disturbance.

I claim:

1. In a protective system for a power distribution network which includes a main line supplying a plurality of consumer branch lines, an automatic reclosing circuit interrupting device connected in the main line and which is responsive upon occurrence of an overload in any branch line to open and immediately reclose the circuits of all consumer lines and a circuit interrupting device in each branch line; an arrangement for tripping any of the branch line interrupting devices upon a continuing overload condition in any such line, said tripping arrangement comprising, a transformer for each branch line having its primary connected in the branch line, electro-responsive means controlling the operation of each of said branch line interrupting devices, and relay means responsive to branch line current for connecting the electro-responsive means related to a branch line in which an overload occurs to the secondary side of the associated transformer upon the initial opening operation of said main line interrupting device.

2. A tripping arrangement as dened in claim 1 wherein said relay means is comprised of a pair of relays energized from the secondary side of the associated transformer, one of said relays when energized closes the energizing circuit of the second relay, said second relay is provided with a time delay opening device and when energized serves to condition the circuit between the transformer secondary and the electro-responsive means, and said circuit is completed through contacts closed by said first relay upon its return to a deenergized position as said main line circuit interrupting device opens.

ERWIN KERN.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,105,392 Wright July 28, 1914 2,050,882 Fitzgerald I Aug. 11, 1936 2,337,713 Garlington Dec. 28, 1943 

